Corner lock construction



2 Shee'ts-Sheet 1 Filed Aug. 12. 1944 July 5, 1949. R. M. DUNNING CORNER LOCK CONSTRUCTION 2 Sheets-Sheet 2 Filed Aug. 12, 1944 atented July 5, 1949 CORNER LOCK CONSTRUCTON Robert M. Dunning, St. Paul, Minn., assignor to Waldorf Paper Products Company, St. Paul, Minn, a corporation of Minnesota Application August 12, 1944, Serial No. 549,143

My invention relates to an improvement in corner lock construction wherein the upstanding corners of a carton or the like may be firmly locked together.

A feature of the present invention lies in the fact that the corners are so locked together that an outward pressure upon the upstanding walls of the carton can not open the box without tearing the same. When in locked position a tab forming a part of a flange hingedly secured to one upstanding side wall of a carton engages in a slot in the other adjacent upstanding wall of the carton. This tab and slot arrangement is such that outward pressure against the walls can not force them apart without tearing the material of the side walls.

A feature of the present invention lies in the provision of a lock which is double acting and which holds the two parts connected from relative movement in any direction. As a result once the lock is engaged relative movement between the parts engaged may not take place.

A further feature of the present invention lies in the provision of a tab having edges thereupon which engage in slots in the adjacent side wall of a carton which slots extend parallel to edges of the tab. As a result a double acting lock is easily produced.

A further feature of the present invention lies in the provision of a corner lock between two carton walls, one of which is provided with a flap arranged to overlie a portion of the other wall, and the other wall being cut away at an angle to permit the one side wall to fold beyond its normal relation with the other side wall. The flap and the other side wall are provided with cooperating tongue and groove means which are locked as the one side wall is folded back into normal folded position.

These and other objects and novel features of 7 Claims. (Cl. 229-35) my invention will be more clearly and fully set assembly of my carton.

Figure 6 is a view similar to Figures 4 and 5 2 showing the corner locks on the end of the carton engaged. V.

The carton illustrated is typical of a type of carton upon which my corner lock may be incorporated. Howeverfmy corner lock may be used on other types of cartons if it is so desired.

The carton A illustrated, discloses a top panel III, a rear wall panel II, a bottom panel l2, and a front wall panel l3 connected along parallel fold lines l4, l5, and IS. A closing flap I! having a projecting tab or ear is thereupon is foldably connected to the top panel 10 along the fold line 20. A slot 2| is provided in the front panel I3 for receiving the tab l9 to lock the carton closed.

End walls 22 and 23 are connected to the bottom panel l2 along parallel fold lines 24 and 2!. Corner flaps 26 and 21 as well as corner flaps 29 and 30 are likewise connected to the front and rear panels 13 and II respectively along the parallel fold lines 24 and 25. Side flaps 3| and 32 are likewise connected along the fold lines 24 and 25 to the ends of the top panel II.

The ends walls 22 and 23 are provided with inclined edges 33, 34, 35, and 36, respectively. The inclined edges 33 and 35 permit the rear panel II to be folded to an acute angle with respect to the bottom panel I2. In the foldin operation of the box the front and rear panels may thus be folded beyond the normal position which permits interengagement of the locks.

A substantially U-shaped slot is provided in each end wall for cooperation with each of the corner flaps. The slot 31 includes a out line 39 and a spaced out line 40, both of which extend radially with respect to the Junction of the fold lines 24 and IS. A connecting cut line 4| connects the ends of the out lines 39 and 40 most closely adjacent this junction. It is not essential that the cut lines 39 and 40 extend radially from the junction of fold lines l5 and 24, but such a construction is typical and has certain advantages over other constructions.

A similar slot 42 is provided in opposed relation to the slot 31. The slot 42 is substantially U-shaped in form including spaced out lines 43 and 44 which are shown as extending radially from the intersection between the score lines l3 and 24. A out line 45 connects one end of the out lines 43 and 44.

Similar slots are provided in the end wall 23. The slots 46 and 41 are identical to the slots 81 and .42. The slot 46 includes radial cut lines 49 and 50 and a connecting out line 5|. The slot 41 includes cut lines 52 and 53 which extend radially from the intersection between the score lines l6 and 25 and includes aconnecting out line 54.

Tabs or flaps 55 and 66 are secured to the corner flaps 26 and 21 along aligned fold lines 5I and 59. A out line 60 extends from the juncture between the fold line 51 and the edge of the blank radially toward the intersection between the fold lines l6 and 24. A part of the carton is notched out along the line 6| which connects the edge of the blank with an intermediate point on the out line 66. The tab is likewise provided with a radial out line 62. A tab or ear 69 projects beyond this out line 62 as illustrated.

All of the corner fiaps are similarly constructed. The corner flap 21 is provided with a out line 64 which extends toward the intersection between the fold lines I8 and 25. The carton is notched along the line 65 and is cut along the radial line 66, the tab or ear 6'I projecting beyond the cut line.

The corner member 36 is provided with a out line 69 extending toward the intersection of the fold lines l5 and 24. The corner member is notched out along the line 10 and is out along the radial line II. The tab or ear I2 projects beyond this out line H as illustrated.

The tab 30 is provided with a out line I3 extending toward the juncture of the fold lines l5 and 25. This corner member is notched along the line It and terminates along the out line 15, the tab or ear I9 projecting beyond this line.

One of the reasons for defining various of the cut lines as extending radially from an intersection between fold lines lies in the fact that by such description the principle of the present invention can be most readily described. It is desirable that certain of the cut lines of the corner flaps coincide with certain of the cut lines defining the U-shaped slots in the end walls of the carton. By illustrating these out lines as extending in radial directions the showing and description is simplified although this radial position of the cut lines is actually unnecessary.

The blank formed as described is folded in the ste s illustrated in Figures 4, 5, and 6 of the drawings. Fi ure 4 illustrates the end flaps 22 and. 23 as well as the corner flaps 26, 21. 29 and 99 folded u wardly to substantially right angles with respect to the bottom panel l2. From the position illustrated in Figure 4 the carton is folded along the fold lines I I and IS, the corner flaps 26 through 90 extending outwardly of the end walls 22 and 23. The corner fiaps are folded beyond right angular position into the position shown in Figure 5 of the drawings. In this posit on the cut lines such as 64 and 13 in the corner fia'os 21 and 30 coincide with, or are slightly below the cut lines 56 and 62 of the slots 46 and 41. The tabs or fingers II and 19 which are defined by the cut lines previously described are then pressed inwardly so that upon folding of the front and rear walls II and I3 into vertical posit on as illustrated in Figure 6 of the drawings the fingers II and I9 pass through the slots 46 and 41. When the front and rear walls II and I9 reach vertical position as shown in Figure 6 the locks are engaged and no further folding may take place along the fold lines 15 and I6.

It will be noted that the fingers II and I9 proiect beyond the end of the out line 49 and that the end of the finger I9 projects beyond the end of the out line 53. Thus the fingers II and 19 are definitely held from pivoting beyond a position in which the front and rear walls ll 4 and I3 are vertical. Figure 6 illustrates the fingers II and I9 extending beyond the relatively short cut lines 49 and 53, locking the wall panels II and I3 from pivoting past the vertical.

It will also be noted that the ends of the fingers II and I9 extend closely adjacent the free ends of the cut lines50 and 52. As the portion of the box defined by the U-shaped slots 46 and 4'! lies exteriorly of the fingers II and I9, these portions tend to urge the fingers II and I9 inwardly. As a result the edges of the corner flaps defined by the out lines 66 and I5 engage against the cut lines 52 and 56 respectively and therefore prevent the carton from folding back into the position illustrated in Figure 5. Therefore once the carton is folded into the position illustrated in Figures 2 and 6, the various wall panels are locked together so that no more relative folding may take place.

In the particular box illustrated the flaps 55 and 56 may then be folded down to a position parallel the bottom panel I 2 and the top l6 may be folded to enclose these flaps. The front flap l9 engages into the slot 2| so as to lock the cover closed. The sideflaps 3| and 32 extend between the end wall panels 22 and 26 and the various ears 63, I2, 61 and 16. The side flaps are thus held parallel with the end walls in the manner illustrated in Figure 3 of the drawings.

In accordance with the patent statutes, I have described the principles of construction and operation of my corner lock construction, and while I have endeavored to set forth the best embodiments thereof, I desire to have it understood that obvious changes may be made within the scope of the following claims without departing from the spirit of my invention.

Iclaim:

1. A corner lock for paperboard containers including a multi-sided base panel defined along two adjacent sides by fold lines which meet to form a corner therebetween, side wall panels foldably connected to said base panel along said fold lines, one of said side wall panels terminating at said comeralong an end line forming an acute angle with the fold line connecting said one side wall panel to said base panel, a locking slit in said one side wall panel, said locking slit including a pair of slits directed generally toward said corner and a third slit connecting those ends of the slits of said pair most closely adjacent to said corner, a fiap foldably connected to the other of said side walls and located to overlap a portion of said first side wall when said side walls are folded upwardly from said base, a tongue on said flap engageable in said locking slit, said tongue having opposite side edge portions which correspond to and coincide with the slits of said pair when said other wall panel is in upright position with the end of the tongue lying adjacent the end of the locking slit most remote from said corner, said tongue overlying a portion of said one side wall between said locking slit and the fold line connecting said one side wall panel to said base panel when said other side wall is folded against said end line of said one wall panel.

2. A corner lock for paperboard containers including a multi-sided base panel defined along two adjacent sides by fold lines which meet to form a corner therebetween, side wall panels foldably connected to said base panel along said fold lines, one of said side wall panels terminating at said corner along an end line forming an acute angle with the fold line connecting said one side wall panel to said base panel, a locking slit in said one side wall panel, said locking slit including a pair of slits directed generally toward said corner and a third slit connecting those ends of the slits of said pair most closely adjacent to said corner, the slit of said pair farthest from the fold line connecting said one panel to said base panel extending a greater distance from said corner than the other slit of said pair, a flap foldably connected to the other of said side walls and located to overlap a portion of said first side wall when said side walls are folded upwardly from said base, a tongue on said flap engageable in said locking slit, the end of said tongue extending farther from said corner than the end most remote from said corner of said one slit of said pair, and having a side edge portion which corresponds to and coincides with the other slit of said pair when said other wall panel is in upright position, said tongue overlying a portion of said one side wall between said locking slit and the fold line connecting said one side wall panel to said base panel when said other side wall is folded against said end line of said one wall panel.

3. A corner lock for paperboard containers including a multi-sided base panel defined along two adjacent sides by fold lines which meet to form a corner therebetween, sidewall panels foldably conected to said base panel along said fold lines, one of said sidewall panels terminating at said corner along an end line forming an acute angle with the fold line connecting said one side wall panel to said base panel, a locking slit in said one side wall panel, said locking slit including a pair of spaced slits transverse to an are having said corner as its center, and a third slit connecting those ends of the slits of said pair most closely adjacent to said corner, the slit nearest the fold line connecting said one side wall panel to said base panel extending iarther from said corner than the other slit of said pair, a flap foldably connected to the other of said side walls and located to overlap a portion of said first side wall when said side walls are folded upwardly from said base, a tongue on said flap engageable in said locking slit, the end of said tongue extending farther from said corner than the end most remote from said corner of said other slit of said pair when engaged in said locking slit, said tongue having a side edge portion which corresponds to and coincides with a portion of said one slit of said pair when said other side Wall panel is in upright position, said tongue overlying a portion of said one side wall between said locking slit and the fold line connecting said one side wall panel to said base panel when said other side wall is folded against said end line of said one wall panel,

4. A corner lock for paperboard containers including a multi-sided base panel defined along two adjacent sides by fold lines which meet to form a corner therebetween, side wall panels foldably connected to said base panel along said fold lines, one of said sidewall panels terminating at said corner along an end line forming an acute angle with the fold line connecting said one side panel to said base panel, a U-shaped locking slit in said one side wall panel, the opposed sides of said slit being generally directed toward said corner and the cut end of said U-shaped slit being on the end of the slit closest said corner, a flap foldably connected to the other of said side walls and located to overlap a portion of said first side wall when said side walls are folded upwardly from said base, a tongue on said flap having its free end directed away from said corner end engageable in said locking slit, said tongue having opposite side edge portions which correspond to and coincide with the apposed sides of said slit when said other wall panel is in upright position, said tongue'overlying a portion of said one side wall between said locking slit and the fold line connecting said one side wall panel to said base panel when said other side wall is folded against said end line of said one wall panel.

5. A paperboard container including a rectangular base panel, defined on its four sides by fold lines, opposed end walls connected to said base panel along two opposed fold lines, and side walls connected to said base panel along the remaining opposed fold lines, the fold lines connecting said side walls to said base panel meeting said fold lines connecting said end walls to said base panel to formcorners, the end edges of said end walls terminating along end lines at acute angles to the fold lines connecting the respective end walls to said base panel, said end lines permitting said side walls to fold upwardly beyond vertical position when said end walls are in vertical position, a locking slit, a pair of locking slits in each end wall, one looking slit being provided adjacent each of said corners, each locking slit including a pair of spaced slits extending transversely to an arc having theadjacent corner as a center, a connecting slit connecting those ends of the spaced slits most closely adjacent the adjacent corner, the slit of each'pair nearest the fold line connecting the respective end wall tosaid base panel extending farther from the adjacent corner than the other slit of each pair, a fiap foldably connected to each end of each side wall and located to overlap a portion of said end walls when said side and end walls are folded upwardly from said base, atongue on each flap engageable in a coresponding locking slit, the end of each tongue projecting beyond the end of the other slit of said pair of slits of the corresponding locking slit in a direction away from the adjacent corner, and each tongue having a side portion which corresponds to and coincides with a portion of said one slit of said pair of the corresponding locking slits when said side and end walls are in vertical position, said tongues overlying a portion of said end walls between said locking slits and the fold lines connecting said end walls to said base panels when said side walls are folded beyond vertical position into engagement with the end lines of said end walls.

6. A paperboard container including a rectangular base panel defined on its four sides by fold lines, opposed end walls connected to said base panel along two opposed fold lines, and side walls connected to said base panel along the remaining opposed fold lines, the fold lines connecting said side walls to said base panel meeting said fold lines connecting said end walls to said base panel to form corners, the end edges of said end walls terminating along end lines at acute angles to the fold lines connecting the respective end walls to said base panel, said end lines permitting said side walls to fold upwardly beyond vertical position when said end walls are in vertical position, a locking slit, a pair of locking slits in each end wall, one locking slit being provided adjacent each of said corners, each locking slit including a pair of spaced slits extending transversely to an are having the adjacent corner as a center, a connecting slit connecting the spaced slits, the slit of each pair nearest the fold line connecting the respective end wall to said base panel extending farther from the adjacent corner than the other slit of each pair, a as foldably connected to each end oi each side wall and located to overlap a portion of said end walls when said side and end walls are folded upwardly from said'base, a tongue on each flap engageable in a corresponding locking slit, each tongue projecting beyond the end of the other slit of said pair of slits of the corresponding locking slit, and each tongue having a side portion which corresponds to and coincides with a portionof said one slit of said pair of the corresponding locking slits when said side and end walls are in vertical position, said tongues overlying a portion of said end walls between said locking slits and the fold lines connecting said end walls to said base panels when said side walls are folded beyond vertical position into engagement with the end lines of said end walls, a cover panel hingedly connected to a side wall. locking flaps hingedly connected to the sides of said cover and foldable to overlie portions of said end walls, and a, projecting tongue on each flap, the projecting tongues of the two flaps overlying each end wall being in opposed relation. said locking flaps on said cover panel being engageable between said projecting tongues and the end walls.

7. A corner lock for paperboard containers including a multi-sided base panel defined along two adjacent sides by fold lines which meet to form a corner therebetween, side wall panels folda-bly connected to said base panel along said fold lines, a locking slit in one of said side wall panels, said slit defining a tongue having a free end and opposite side edges directed diagonally in the general direction of said corner, a flap foldably connected to the other of said side wall panels and overlapping a portion of said one side wall panel in upright position of said panels, a locking tongue on said flap having opposite side edges directed diagonally away from said corner, said tongues overlapping with said locking tongue extending through said slit, the opposite diagonally extending side edges on said tongues arranged in registry in overlapped condition of said tongues.

ROBERT M. DUNNING.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 199,675 Wolf Jan. 29, 1878 454,636 Brown et al June 23, 1891 1,319,263 Baker 1 Oct. 21, 1919 1,544,311 Graflenberger June 30, 1925 2,067,740 Uzell Jan. 12, 1937 FOREIGN PATENTS Number Country Date 88,045 Sweden Oct. 1, 1936 

